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Eras & periods

Every run targets one era (also called a period), passed as --period. An era is a CMS data-taking period; choosing one selects the matching datasets, corrections and NanoAOD version.

Run 3 eras (current)

--period Description √s NanoAOD
Run3_2022 2022, pre-ECAL repair 13.6 TeV v12
Run3_2022EE 2022, post-ECAL repair ("EE") 13.6 TeV v12
Run3_2023 2023, pre-BPix 13.6 TeV v13
Run3_2023BPix 2023, post-BPix install 13.6 TeV v13
Run3_2024 2024 13.6 TeV v15
Run3_2025 2025 (future) 13.6 TeV —

Run 2 eras (legacy)

Run2_2016_HIPM, Run2_2016, Run2_2017, Run2_2018 (13 TeV). Still defined, but new development targets Run 3.

Why the split into sub-eras?

The detector and its calibration change within a year, so CMS treats those segments as separate eras for analysis:

  • 2022 splits at the ECAL endcap repair → Run3_2022 (before) and Run3_2022EE (after).
  • 2023 splits at the pixel-detector "BPix" installation → Run3_2023 and Run3_2023BPix.

Each sub-era has its own corrections and luminosity, which is exactly why the configuration system has a per-era layer: FLAF/config/<era>/ and <analysis>/config/<era>/ carry the era-specific datasets and overrides.

What an era controls

  • Datasets — config/<era>/datasets.yaml lists the samples available for that era, including the correct NanoAOD version path on DAS.
  • NanoAOD version — the table above; the dataset entries point at the right vNN campaign.
  • Corrections — pileup, b-tagging, trigger and other scale factors are era-specific.
  • Signals — resonant/non-resonant signals exist for some eras and not others (for instance, several signal families are not produced for Run3_2024).

Running several eras

A task runs one era at a time. To cover multiple eras, launch the task once per era (often scripted), or, in CI, list them in the *_eras variable (e.g. Run3_2022 Run3_2022EE Run3_2023 Run3_2023BPix, or ALL). See the integration pipeline.

--period must match an existing era directory

If you pass an era that has no config/<era>/ (or whose datasets are not defined), config loading fails — and if a run unexpectedly drops into InputFileTask and queries DAS for nothing, a wrong --period/--version combination is the usual cause. See Troubleshooting.

Adding a new era

Adding an era means creating its per-era config directories in both the framework and the analysis, wiring it into the CI era lists, and listing it in test-setup-loading. The full procedure is in Datasets.